2002 Sequoia SR5 not starting


New Member
Dec 22, 2018
I've taken good care of our family car and have been able to maintain it with regular maintenance for the past 16 years, 176000 miles. The last issue, starter went bad has left the truck dead...

A bit of background:
  • Check engine light was on, codes were for vacuum issues, started replacing hoses (past 2 years) engine light would go off for some time, show up again with same/similar codes, replaced gas cap, more hoses and all good.
  • VSC and TRAC lights came on, brake got really hard and would stop with enough distance. Brake fluid was black, flushed brake lines but no good. Replaced master cylinder, purged lines and it was happy again.
  • No lights or issues for some 3 months after break issues.
Then trouble started, I heard an interesting noise when starting and I figured that the starter was going bad. Researched and found out where the starter is located and postponed fix due to a trip for work. Same day I come back when the starter died and had to tow the truck home.

To prepare for the repair I wanted to have a clean under hood (this is likely my biggest mistake here) so I used simple green and water to hose debris, dust and some grime off.

I got the starter, and some help to do the repair, the knock sensor connector's clip broke but otherwise seems intact and making connection, added high temp silicone to hold in place and reassembled the intake manifold. Cleaned Throttle body while it was out and put it back and reconnected all hoses and electrical. The car started rough, and idled low at first and it seemed to hunt for idle and finally idled normally but it did not accelerate and had a couple of miss fires. Pulled the codes and saw the miss fires, some vacuum so I thought (Darn should have changed all the gaskets) got the gaskets, and replaced the lower one for the intake and the throttle body and resembled. It started again briefly and died. Pulled codes and saw P1126 (magnetic clutch and likely throttle problems).

That's when I threw in the towel and took it to the shop where they replaced the throttle body with one that was clearly from a donor truck and no luck. I took the truck back to cut my losses short.

Since I've replaced the ECU, had to swap the Immobilizer EEPROM from the original ECU to the used ECU so it would send sparks (simple surface mount chip swap) but it did not want to start.

So far it seems unlikely that the throttle body and the sensors on it and the ECU are the culprit but I'm at a loss as to what it could be. I would hope to get some more mileage out of this truck but I need help.

Any ideas from anyone here as to what I should check would be appreciated.

The next steps I would take are:
  • Disconnect all wire harness connections and spray them with electronics cleaner.
    • Get back into the Knock sensor area and check that the connection is good. If there is a way to check that without tearing the intake apart again I'm all ears.
    • Check spark plugs and coils (don't have the tools for this last one)
  • Replace the ABS control module (if not to expensive)
If all this fails then I'm going to either donate it to charity or Junk it but I would really hate to do that as I think the truck is still alive in there and can be brought back.

Thanks in advance for any tips.
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